What does this mean in practice?
When carrying out regulated procedures, you should always consider whether there are ways to refine what you are doing to reduce pain, suffering, distress, or harm to the animal, provided this does not compromise the scientific objectives of the study.
Refinements may include:
- Using anaesthesia, whether local or general, where appropriate
- Providing analgesia to reduce pain or inflammation
- Applying scoring and monitoring systems with clear trigger points, so action can be taken early to minimise harm. This may include supportive care or, where necessary, euthanasia.
Actively reviewing and applying refinements is a key part of meeting your responsibilities under this Standard Condition.
How do I comply with PIL Standard Condition 4?
Alongside PIL Standard Condition 1, it is essential to apply refinement wherever possible. Any action that reduces or prevents pain, suffering, distress, or harm to an animal is a refinement. By actively managing this condition, you also provide evidence that you are meeting several other responsibilities as a licence holder.
Start by reviewing your handling and procedural techniques. For those working with mice, one of the most effective refinements is the routine use of refined handling methods (often known as low‑stress or tunnel handling). This significantly reduces anxiety and stress compared to traditional tail handling. Further guidance is available on the NC3Rs mouse handling microsite.
For surgical procedures, the use of appropriate anaesthesia and analgesia is expected. However, for less invasive or “minor” procedures, the refinements may be less obvious. Many project licences include different anaesthesia options, such as:
- AA – No anaesthesia
- AB – Anaesthesia with recovery
- AC – Anaesthesia without recovery
- AD – Use of neuromuscular relaxants
You should always consider whether anaesthesia would meaningfully reduce harm, bearing in mind that anaesthesia must not be used solely for restraint. If a procedure causes site sensitivity or vocalisation, and the licence authority allows it, the use of anaesthesia may be an appropriate refinement to reduce harm.
Similarly, consider refinement when planning sample collection. For example, if a blood sample is only required once and repeated samples are not necessary, could it be taken under terminal anaesthesia or post‑mortem instead?
For commonly performed procedures in smaller mammals such as rats and mice, local anaesthetics may not always be used routinely. However, during techniques such as tail vein or saphenous blood sampling, local anaesthetic options should be available and considered to minimise pain.
For larger species such as pigs or non‑human primates, refinement often focuses on training and habituation. Spending time training animals to present limbs, enter transport crates, or accept restraint cages reduces stress and avoids the need for forceful restraint. These approaches significantly reduce harm and are strong examples of fulfilling this Standard Condition in practice.
What resources are available to support me?
The NC3Rs provides a wide range of resources and microsites to support the refinement of procedures. Another valuable resource are the Procedures with Care tutorials on this platform which cover administration of substances & aseptic technique. These include filmed demonstrations of common techniques alongside guidance on potential refinements that can be applied in practice.
Within your establishment, the NIO, NACWO, and NTCO are key sources of advice when considering refinements to your work. Even when you are working in a novel area, these individuals can draw on their own experience or contact colleagues across other establishments to identify suitable refinements. Animal care staff, in particular, bring extensive practical knowledge gained from observing a wide range of procedures over many years.
As a licence holder, you also play an important role in identifying opportunities for refinement through your own experience. Do not assume that a procedure cannot be improved simply because it has always been done a certain way. Many widely accepted refinements, such as refined handling, only exist because individuals challenged established practices. By discussing your observations with colleagues and animal care staff, you are likely to identify small but meaningful improvements that support animal welfare and compliance with your licence conditions.
Throughout your career, you are likely to notice informal or anecdotal observations that highlight opportunities for refinement. Stay open to new ideas and always consider how even small changes to a study can have a significant positive impact on animal welfare.
What happens if I don’t comply with PIL Standard Condition 4?
This Standard Condition can be breached, and, as with other conditions, the consequences will largely depend on intent and circumstances. No Personal Licence (PIL) holder should ever carry out a procedure with the intention of causing harm. While some level of harm may be unavoidable in animal research, it should never be the objective.
In most cases of non‑compliance, the incident will be investigated by the ASRU enforcement team. As the PIL holder, you would be expected to provide evidence showing how you attempted to uphold the condition, including any steps taken to reduce harm or apply refinement.
It is important to remember that you are personally responsible for the procedures you carry out, alongside the Project Licence (PPL) holder. If a supervisor or another licence holder suggests ignoring signs of pain or suffering, this does not remove your responsibility. For example, choosing not to apply a refinement, such as reusing needles to save money or extending a study to obtain more data when the animal is suffering, will reflect on you, not on the person who advised it.
Legally, responsibility sits with the individual performing the procedure. Saying that someone senior told you it was acceptable is not a defence. Acting in the animal’s best interests and within your licence conditions is always your obligation.
How does ASRU assess compliance with PIL Standard Condition 4?
ASRU assesses compliance by reviewing whether Personal Licence holders take appropriate precautions to prevent or minimise pain, suffering, distress, or discomfort arising from regulated procedures.
During an inspection, ASRU may review evidence of training on the controls and limitations within the project licence protocols the PIL holder is working under. Inspectors may also speak with the PIL holder, Project Licence Holder, NACWO, and NVS to confirm understanding, competence, and consistent application of these controls and limitations in practice.
How do I know if I am complying with PIL Standard Condition 4?
You can be confident you are fulfilling this Standard Condition by working conscientiously and carrying out all procedures with care, while actively looking for opportunities to apply refinement wherever possible.
Do not assume that established methods are the only option. For example, just because a drug or compound has always been administered via a particular route does not mean alternative, less invasive routes are unsuitable. In some cases, compounds may be effectively delivered through food or drinking water, potentially reducing stress and harm to the animal.